1. Field of the Invention
The present invention relates generally to a bright meter and more specifically to a needle brightened on a dial of a bright meter suitable for use in speed meters, tachometers, etc. arranged in a dashboard of an automotive vehicle, for instance.
2. Description of the Prior Art
In some automotive vehicles, bright meters whose dial and needle are brightened by light are arranged in a dashboard of the vehicle. FIGS. 1A to 1C show a dial and a needle of a prior-art bright speed meter, by way of example.
In these drawings, a dial 1 is made of a light transmissible (i.e. transparent) synthetic resin. The surface of the dial is printed by a semitransparent or an opaque colored paint, and dial numerals, characters, graduations, etc. are formed by removing the paint on the dial 1 into the shapes corresponding thereto. A light guide plate 3 is so disposed under the dial 1 as to introduce light emitted from a light source 2 to a needle axle 5 as a background illumination light, so that the whole surface of the dial 1 or the numerals and the graduations can be illuminated from under by the light source 2 and through the light guide plate 3.
A needle 4 arranged at the center of the dial 1 is made of the same light transmissible material as that of the dial 1 and the light guide plate 3. The needle 4 is fixed to a needle axle 5 rotatable according to the magnitude of vehicle speed, so that one end of the needle 4 rotates on the dial 1.
The light guided through the light guide plate 3 as shown in FIG. 1B is reflected upward from a central inner conical reflecting surface 3a, being introduced into the central portion of the needle 4, and then reflected again radially outward from a reflecting surface 4b formed at the needle axle 4a to a free end of the needle 4. Further, in FIG. 1B, the numeral 4C denotes a metallic needle cap.
On the other hand, as shown in FIG. 1C, a reflecting layer 4d (e.g. orange-colored) is formed by printing on the lower needle surface along the needle longitudinal direction, so that part of the light introduced into the needle is reflected upward.
In the above-mentioned prior-art bright meter, however, there still exists a problem in that the needle recognizability is not satisfactory according to the surrounding illumination conditions or driver's eye position, because the illumination area of the bright needle 4 is not broad enough for the driver.